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Science China Earth Sciences 2011年第12期54卷 1830-1844页

作者： WHANG Y. C catholic university of america

Interaction of the solar wind with the interstellar medium leads to the formation of the heliosphere and termination shock. This article addresses three aspects of the plasma and magnetic field on two sides of the heliopause：（1） The interstellar magnetic field surrounding the heliopause. In the limit of very low plasma β-ratio an analytical solution is obtained for the 3D interstellar magnetic field by means of a line dipole method. The undisturbed magnetic field in the upstream is allowed to have an arbitrary inclination angle. The solution describes the heliosphere as having a blunt-nosed geometry on the upwind side and approaching a cylindrical geometry on the downwind side. The distortion of the magnetic field can penetrate very deep into the interstellar space. （2） Interaction of the interstellar neutral hydrogen with the global solar wind. The ionization process leads to removal of interstellar neutral hydrogen in the heliosphere： on the upwind side, 90% of hydrogen depletion occurs inside 60 AU, the hydrogen density changes rapidly inside 10 AU. A hydrogen cavity forms inside -4 AU; the cavity extends on the downwind side to form a long cavity wake. Outside the cavity and cavity wake, pickup protons are produced, they cause deceleration and heating of the solar wind. The wind speed and temperature also increase steadily with heliolatitude caused by the latitudinal increase in wind speed at the inner boundary. （3） The global geometry of the termination shock. The termination shock has been treated as having a closed geometry in previous heliosphere models. This study presents a new perspective that the global termination shock may have a bow-shaped open geometry. The termination shock forms on the upwind side because the forward motion of the supersonic solar wind is blocked at the blunt-nosed heliopause. However, the heliopause likely to be open on the downwind side; the motion of the supersonic solar wind is unobstructed for shock formation. Thus, the globa

关键词： solar wind interstellar medium magnetic fields plasmas magnetohydrodynamics (MHD)

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RADIATIVE TRANSPORT IN THE DELTA-P1 APPROXIMATION FOR LAMINAR OPTICAL TOMOGRAPHY

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Journal of Innovative Optical Health Sciences 2009年第2期2卷 149-163页

作者： BAOHONG YUAN Department of Biomedical Engineering catholic university of america Washington DC 20064 USA

To provide a computational efficient forward model with moderate accuracy for rapid 3D optical tomography in small volumes,radiative transport in the delta-P1 approximation combined with the approximation of the reciprocity was *** of optical signals caused by absorption and fluorescence heterogeneities submerged in a resin-based liquid phantom with background parameters close to rat brain tissues were measured using a recently constructed laminar optical tomography *** measured perturbations were used to examine the theoretically calculated fluence perturbations based on the delta-P1 approximation and the reciprocity *** show that the errors between the predicted and measured data are acceptable,especially for fluorescence perturbations.

关键词： Photon migration tomography fluorescence delta-P1 approximation reciprocity approximation.

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On the Performance of the Energy Detector Subject to Impulsive Noise in κ-μ, α-μ, and η-μ Fading Channels

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Tsinghua Science and Technology 2017年第4期22卷 360-367页

作者： Jos V.M.Cardoso Wamberto J.L.Queiroz Hang Liu Marcelo S.Alencar Department of Electrical Engineering Federal University of Campina Grande Department of Electrical Engineering and Computer Science The Catholic University of America

This paper presents a unified theoretical analysis of the energy detection of Gaussian and M-PSK signals in κ-μ,α-μ,and η-μ fading channels at the output of an energy detector subject to impulsive noise（Bernoulli-Gaussian model）. As a result, novel, simple, and accurately approximated expressions for the probability of detection are derived. More precisely, the generalized Gauss-Laguerre quadrature is applied to approximate the probability of detection as a simple finite sum. Monte Carlo simulations corroborate the accuracy and precision of the derived approximations. The results are further extended to cooperative energy detection with hard decision combining information.

关键词： spectrum sensing energy detector fading channel impulsive noise

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变权综合评价法在山区道路安全评价中应用

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系统工程 2010年第5期28卷 85-88页

作者：游克思孙璐顾文钧东南大学交通学院江苏南京210096 Department of Civil Engineering Catholic University of America

通过对山区道路交通事故资料调查分析,研究了道路条件对行车安全影响,在此基础上从四个方面建立了相应的评价指标体系。将变权原理引入模糊综合评价,采用惩罚型变权模式,建立了山区道路安全评价变权综合评价模型。通过实例应用,分别采... 详细信息

通过对山区道路交通事故资料调查分析,研究了道路条件对行车安全影响,在此基础上从四个方面建立了相应的评价指标体系。将变权原理引入模糊综合评价,采用惩罚型变权模式,建立了山区道路安全评价变权综合评价模型。通过实例应用,分别采用常权和变权两种方法计算,结果表明,采用变权模糊综合评价法得到的结果更容易区分评价等级,能够突现出部分指标因素在较差情况下时对道路整体安全水平的影响,评价结果更接近实际。

关键词：山区道路安全变权综合评价

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Transient response of a beam on viscoelastic foundation under an impact load during nondestructive testing

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Earthquake Engineering and Engineering Vibration 2005年第2期4卷 325-333页

作者：孙璐罗飞全陈东晖 Department of Civil Engineering Catholic University of America620 Michigan Ave.N.E.Washington DC.20064USA AssistantProfessor Department of Civil Engineering Catholic University of America620 Michigan Ave.N.E.Washington DC.20064USA Graduate Student

Beam responses under an impact NDT load are studied using the Fourier and Laplace transforms. Numerical computation is performed for a parametric study of beam and load parameters. It is shown that under an impact load, the time duration for displacement to vanish is ten times longer than that for velocity and acceleration. The maximum response is achieved first in acceleration, followed by velocity, and finally displacement, all of which occur before the impact load is removed. At the moment that the impact load is removed from the beam, there is a discontinuity in the velocity and acceleration responses, but not in displacement response. The effect of K and ph on beam response is much less significant than that of EI and C, which have similar effect on beam response. As El increases, peak values of displacement, velocity and acceleration response decrease, The effect of K on beam response only becomes appreciable after the impact load is removed. While the peak of displacement remain almost unchanged large K values than for small K values. as K increases, the displacement response decays to zero faster for

关键词： beam acceleration impact load Laplace transform Fourier transform

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Alcohol-induced alterations of the hepatocyte cytoskeleton

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World Journal of Gastroenterology 2010年第11期16卷 1358-1365页

作者： Blythe D Shepard Pamela L Tuma Department of Biology The Catholic University of America

The hepatocyte cytoskeleton consists of three fi lamentous networks: microtubules, actin microfi laments and keratin intermediate filaments. Because of the abundance of the proteins that comprise each system and the central role each network plays in a variety of cellular processes, the three fi lament systems have been the focus of a host of studies aimed at understanding the progression of alcohol-induced liver injury. In this review, we will briefly discuss the hepatic organization of each cytoskeletal network and highlight some components of each system. We will also describe what is known about ethanol-induced changes in the dynamics and distributions of each cytoskeletal system and discuss what is known about changes in protein expression levels and post-translational modifi cations. Finally, we will describe the possible consequences of these cytoskeletal alterations on hepatocyte function and how they might contribute to the progression of liver disease.

关键词： Ethanol Hepatotoxicity Tubulin Actin Keratin

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碳纳米管纱在应力下的压阻效应:现象和影响因素(英文)

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新型炭材料 2018年第2期33卷 140-154页

作者： Jude C.Anike Kalayu Belay Jandro L.Abot Department of Mechanical Engineering The Catholic University of America Department of Physics Florida A&M University

碳纳米管因机械应力敏感特性而成为传感器的理想材料。单原子层厚度的石墨烯片卷曲而成的单壁碳纳米管具有大约1 nm的管径。碳纳米管纺丝形成纱,使其能够用于结构组份中。本文研究了碳纳米管纱的几何尺寸、力学性能和准静态应力加载速... 详细信息

碳纳米管因机械应力敏感特性而成为传感器的理想材料。单原子层厚度的石墨烯片卷曲而成的单壁碳纳米管具有大约1 nm的管径。碳纳米管纺丝形成纱,使其能够用于结构组份中。本文研究了碳纳米管纱的几何尺寸、力学性能和准静态应力加载速率对其压阻效应的影响。应力加载速率影响碳纳米管纱的失效机理和机电特性。高应力加载速率导致拉伸强度的增加和正压阻效应,而低应力加载速率引起较高的应力失效与负压阻效应。碳纳米管纱的压阻传感器系数随应力加载速率基本不变,但其对于应力水平和碳纳米管纱的几何尺寸具有高度依赖性。作为传感器所需的线性压阻关系在高应力加载速率下相关系数为0.995,而在低应力加载速率下相关系数只有0.832。

关键词：压阻效应碳纳米管传感器

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VARIATIONS OF INTERPLANETARY FLUCTUATIONS ACROSS THE BOW SHOCK

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Science China Mathematics 1988年第10期31卷 1240-1254页

作者：魏奉思都亨黄云潮 Beijing Washington D. C. USA Institute of Space Physics Department of Mechanical Engineering the catholic university of america Scientia Sinica

Shell’s transmission model of an MHD wave through a fast shock is not to treat transmission of waves beyond the critical incident angles. Considering that interplanetary fluctuations impinge on the bow shock from all directions, a model studying the interaction between MHD waves and the Earth’s bow shock under ordinary conditions is presented in this paper. The results show that the state of fluctuations undergoes a siginificant jump across the Earth’s bow shock. Both the amplitude of fluctuations and the degree of fluctuation anisotropy increase across the Earth’s bow shock. The calculated probability distribution functions of fluctuations immediately behind the bow shock is very similar to those reconstructed from the observed magnetosheath data. Simulations for the spatial variation in the state of fluctuations behind the bow shock reveal that the fluctuation activities display the dawn-dusk asymmetry higher in the dawn side than in the dusk side. When interplanetary background magnetic field lies in

关键词： interplanetary fluctuation bow shock.

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A new beam asymmetry measurement from pion photoproduction on the neutron using CLAS

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Chinese Physics C 2009年第12期33卷 1369-1372页

作者： D. Sokhan D. Watts F. Klein School of Physics & Astronomy University of Edinburgh Edinburgh EH9 3JZ UK Department of Physics Catholic University of America Washington DC 20064 USA

We present a preliminary analysis of the photon beam asymmetry observable （Z） from the pho- toproduction reaction channel γn → pπ in the invariant mass range 1.6--2.3 GeV. The measurement was obtained using the near-4π CEBAF Large Acceptance Spectrometer （CLAS） at Jefferson Laboratory, USA, employing a linearly polarised photon beam with an energy range 1.1 2.3 GeV, incident on a liquid deuterium target. The measurement will provide new data to address the poorly established neutron excitation spectrum and will greatly expand the sparse world data-set both in energy and angle.

关键词： beam asymmetry photonuclear photoproduction neutron pion.

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An overview of a unified theory of dynamics of vehicle–pavement interaction under moving and stochastic load

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Journal of Modern Transportation 2013年第3期21卷 135-162页

作者： Lu Sun Department of Civil Engineering The Catholic University of America International Institute of Safe Intelligent and Sustainable Transportation & Infrastructure Southeast University

This article lays out a unified theory for dynamics of vehicle-pavement interaction under moving and stochastic loads. It covers three major aspects of the subject： pavement surface, tire-pavement contact forces, and response of continuum media under moving and stochastic vehicular loads. Under the subject of pavement surface, the spectrum of thermal joints is analyzed using Fourier analysis of periodic function. One-dimensional and two-dimensional random field models of pavement surface are discussed given three different assumptions. Under the subject of tire-pavement contact forces, a vehicle is modeled as a linear system. At a constant speed of travel, random field of pavement surface serves as a stationary stochastic process exciting vehicle vibration, which, in turn, generates contact force at the interface of tire and pavement. The contact forces are analyzed in the time domain and the frequency domains using random vibration theory. It is shown that the contact force can be treated as a nonzero mean stationary process with a normal distribution. Power spectral density of the contact force of a vehicle with walking-beam suspension is simulated as an illustration. Under the subject of response of continuum media under moving and stochastic vehicular loads, both time-domain and frequency-domain analyses are presented for analytic treatment of moving load problem. It is shown that stochastic response of linear continuum media subject to a moving stationary load is a nonstationary process. Such a nonstationary stochastic process can be converted to a stationary stochastic process in a follow-up moving coordinate.

关键词： Vehicle-pavement interaction - Random field.Continuum medium - Spectral analysis ~ Green's function.Linear system

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